From: Omar Sandoval <osandov@osandov.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, osandov@fb.com, efault@gmx.de,
paolo.valente@linaro.org
Subject: Re: [PATCH 5/9] sbitmap: fix missed wakeups caused by sbitmap_queue_get_shallow()
Date: Thu, 10 May 2018 10:01:10 -0700 [thread overview]
Message-ID: <20180510170110.GE30485@vader> (raw)
In-Reply-To: <1525969467-12476-6-git-send-email-axboe@kernel.dk>
On Thu, May 10, 2018 at 10:24:23AM -0600, Jens Axboe wrote:
> From: Omar Sandoval <osandov@fb.com>
>
> The sbitmap queue wake batch is calculated such that once allocations
> start blocking, all of the bits which are already allocated must be
> enough to fulfill the batch counters of all of the waitqueues. However,
> the shallow allocation depth can break this invariant, since we block
> before our full depth is being utilized. Add
> sbitmap_queue_min_shallow_depth(), which saves the minimum shallow depth
> the sbq will use, and update sbq_calc_wake_batch() to take it into
> account.
>
> Acked-by: Paolo Valente <paolo.valente@linaro.org>
> Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed -- haha, wait, thanks for picking this one up :)
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
> include/linux/sbitmap.h | 29 +++++++++++++++++++++++++++++
> lib/sbitmap.c | 49 ++++++++++++++++++++++++++++++++++++++++---------
> 2 files changed, 69 insertions(+), 9 deletions(-)
next prev parent reply other threads:[~2018-05-10 17:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-10 16:24 [PATCHSET v3 0/9] blk-mq-sched and sbitmap shallow depth Jens Axboe
2018-05-10 16:24 ` [PATCH 1/9] blk-mq: don't call into depth limiting for reserved tags Jens Axboe
2018-05-10 16:59 ` Omar Sandoval
2018-05-10 16:24 ` [PATCH 2/9] bfq-iosched: don't worry about reserved tags in limit_depth Jens Axboe
2018-05-10 16:59 ` Omar Sandoval
2018-05-10 16:24 ` [PATCH 3/9] bfq: calculate shallow depths at init time Jens Axboe
2018-05-10 17:00 ` Omar Sandoval
2018-05-10 16:24 ` [PATCH 4/9] bfq-iosched: remove unused variable Jens Axboe
2018-05-10 17:00 ` Omar Sandoval
2018-05-10 16:24 ` [PATCH 5/9] sbitmap: fix missed wakeups caused by sbitmap_queue_get_shallow() Jens Axboe
2018-05-10 17:01 ` Omar Sandoval [this message]
2018-05-10 17:09 ` Jens Axboe
2018-05-10 16:24 ` [PATCH 6/9] sbitmap: warn if using smaller shallow depth than was setup Jens Axboe
2018-05-10 17:02 ` Omar Sandoval
2018-05-10 17:09 ` Jens Axboe
2018-05-10 16:24 ` [PATCH 7/9] bfq-iosched: update shallow depth to smallest one used Jens Axboe
2018-05-10 17:03 ` Omar Sandoval
2018-05-10 16:24 ` [PATCH 8/9] kyber-iosched: update shallow depth when setting up hardware queue Jens Axboe
2018-05-10 17:03 ` Omar Sandoval
2018-05-10 16:24 ` [PATCH 9/9] sbitmap: fix race in wait batch accounting Jens Axboe
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